Source audio acoustic leakage detection and management in an adaptive noise canceling system

Abstract

A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is also provided proximate to the speaker to provide an error signal indicative of the effectiveness of the noise cancellation. A secondary path estimating adaptive filter is used to estimate the electro-acoustical path from the noise canceling circuit through the transducer so that source audio can be removed from the error signal. A level of the source audio with respect to the ambient audio is determined to determine whether the system may generate erroneous anti-noise and / or become unstable.

Description

[0001]This U.S. Patent Application is a Division of U.S. patent application Ser. No. 13 / 727,718, filed on Dec. 27, 2012, and claims priority thereto under 35 U.S.C. §121. U.S. parent patent application Ser. No. 13 / 727,718 claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 61 / 645,333 filed on May 10, 2012.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates generally to personal audio devices such as wireless telephones that include adaptive noise cancellation (ANC), and more specifically, to sequenced adaptation of ANC adaptive responses in a personal audio device that uses a secondary path estimate in addition to adaptive anti-noise filtering.[0004]2. Background of the Invention[0005]Wireless telephones, such as mobile / cellular telephones, cordless telephones, and other consumer audio devices, such as MP3 players, are in widespread use. Performance of such devices with respect to intelligibility can be im...

AI Technical Summary

Benefits of technology

[0010]In another feature, the ANC processing circuit detects that the source audio leakage from the output transducer to the reference microphone is, or will be, too great for proper operation and takes action on adaptation of the adaptive filter that generates the anti-noise signal to prevent or remedy improper operation.

Problems solved by technology

However, when the source audio has a very high amplitude, acoustic leakage from the transducer to the reference microphone can cause the adaptive filter that generates the noise-canceling (anti-noise) signal to adapt improperly.

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